<html lang="en">
<head>
<title>M68HC11-Branch - Using as</title>
<meta http-equiv="Content-Type" content="text/html">
<meta name="description" content="Using as">
<meta name="generator" content="makeinfo 4.13">
<link title="Top" rel="start" href="index.html#Top">
<link rel="up" href="M68HC11_002dopcodes.html#M68HC11_002dopcodes" title="M68HC11-opcodes">
<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage">
<!--
This file documents the GNU Assembler "as".

Copyright (C) 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
2000, 2001, 2002, 2006, 2007, 2008, 2009, 2010 Free Software Foundation, Inc.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3
or any later version published by the Free Software Foundation;
with no Invariant Sections, with no Front-Cover Texts, and with no
Back-Cover Texts.  A copy of the license is included in the
section entitled ``GNU Free Documentation License''.

-->
<meta http-equiv="Content-Style-Type" content="text/css">
<style type="text/css"><!--
  pre.display { font-family:inherit }
  pre.format  { font-family:inherit }
  pre.smalldisplay { font-family:inherit; font-size:smaller }
  pre.smallformat  { font-family:inherit; font-size:smaller }
  pre.smallexample { font-size:smaller }
  pre.smalllisp    { font-size:smaller }
  span.sc    { font-variant:small-caps }
  span.roman { font-family:serif; font-weight:normal; } 
  span.sansserif { font-family:sans-serif; font-weight:normal; } 
--></style>
<link rel="stylesheet" type="text/css" href="../cs.css">
</head>
<body>
<div class="node">
<a name="M68HC11-Branch"></a>
<a name="M68HC11_002dBranch"></a>
<p>
Up:&nbsp;<a rel="up" accesskey="u" href="M68HC11_002dopcodes.html#M68HC11_002dopcodes">M68HC11-opcodes</a>
<hr>
</div>

<h5 class="subsubsection">9.22.6.1 Branch Improvement</h5>

<p><a name="index-pseudo_002dopcodes_002c-M68HC11-1244"></a><a name="index-M68HC11-pseudo_002dopcodes-1245"></a><a name="index-branch-improvement_002c-M68HC11-1246"></a><a name="index-M68HC11-branch-improvement-1247"></a>
Certain pseudo opcodes are permitted for branch instructions. 
They expand to the shortest branch instruction that reach the
target. Generally these mnemonics are made by prepending &lsquo;<samp><span class="samp">j</span></samp>&rsquo; to
the start of Motorola mnemonic. These pseudo opcodes are not affected
by the &lsquo;<samp><span class="samp">--short-branches</span></samp>&rsquo; or &lsquo;<samp><span class="samp">--force-long-branches</span></samp>&rsquo; options.

   <p>The following table summarizes the pseudo-operations.

<pre class="smallexample">                             Displacement Width
          +-------------------------------------------------------------+
          |                     Options                                 |
          |    --short-branches           --force-long-branches         |
          +--------------------------+----------------------------------+
       Op |BYTE             WORD     | BYTE          WORD               |
          +--------------------------+----------------------------------+
      bsr | bsr &lt;pc-rel&gt;    &lt;error&gt;  |               jsr &lt;abs&gt;          |
      bra | bra &lt;pc-rel&gt;    &lt;error&gt;  |               jmp &lt;abs&gt;          |
     jbsr | bsr &lt;pc-rel&gt;   jsr &lt;abs&gt; | bsr &lt;pc-rel&gt;  jsr &lt;abs&gt;          |
     jbra | bra &lt;pc-rel&gt;   jmp &lt;abs&gt; | bra &lt;pc-rel&gt;  jmp &lt;abs&gt;          |
      bXX | bXX &lt;pc-rel&gt;    &lt;error&gt;  |               bNX +3; jmp &lt;abs&gt;  |
     jbXX | bXX &lt;pc-rel&gt;   bNX +3;   | bXX &lt;pc-rel&gt;  bNX +3; jmp &lt;abs&gt;  |
          |                jmp &lt;abs&gt; |                                  |
          +--------------------------+----------------------------------+
     XX: condition
     NX: negative of condition XX
     
</pre>
     <dl>
<dt><code>jbsr</code><dt><code>jbra</code><dd>These are the simplest jump pseudo-operations; they always map to one
particular machine instruction, depending on the displacement to the
branch target.

     <br><dt><code>jb</code><var>XX</var><dd>Here, &lsquo;<samp><span class="samp">jb</span><var>XX</var></samp>&rsquo; stands for an entire family of pseudo-operations,
where <var>XX</var> is a conditional branch or condition-code test.  The full
list of pseudo-ops in this family is:
     <pre class="smallexample">           jbcc   jbeq   jbge   jbgt   jbhi   jbvs   jbpl  jblo
           jbcs   jbne   jblt   jble   jbls   jbvc   jbmi
</pre>
     <p>For the cases of non-PC relative displacements and long displacements,
<code>as</code> issues a longer code fragment in terms of
<var>NX</var>, the opposite condition to <var>XX</var>.  For example, for the
non-PC relative case:
     <pre class="smallexample">              jb<var>XX</var> foo
</pre>
     <p>gives
     <pre class="smallexample">               b<var>NX</var>s oof
               jmp foo
           oof:
</pre>
     </dl>

<!-- Copyright 2009 -->
<!-- Free Software Foundation, Inc. -->
<!-- This is part of the GAS manual. -->
<!-- For copying conditions, see the file as.texinfo. -->
   </body></html>